Guard against panics from unchecked type assertions

Replace two unchecked type assertions that could crash the server:

- server.go: the file-transfer logger built remoteAddr via a bare
  ctx.Value(contextKeyReq).(requestCtx) assertion, which panics if the
  context value is absent or the wrong type. Use the comma-ok form and
  degrade to an empty string.

- access.go: the legacy (< v0.17.0) AccessBitmap YAML array path used
  byte(v.(int)) with no element-type or bounds check, panicking on a
  non-int element or an array longer than the [8]byte bitmap. Iterate the
  slice from the type switch, bounds-check the index, and comma-ok each
  element, returning a wrapped error so a malformed user file fails to
  load loudly instead of crashing the server.

Add regression tests for the non-int and oversized legacy array cases.

1 files changed, 10 insertions, 0 deletions

diff --git a/hotline/access_test.go b/hotline/access_test.go
index 2c5b8f4..65d29be 100644
--- a/hotline/access_test.go
+++ b/hotline/access_test.go
@@ -75,6 +75,16 @@ func Test_accessBitmap_UnmarshalYAML(t *testing.T) {
 			wantErr:  false,
 		},
 		{
+			name:     "legacy array with non-int element returns error",
+			yamlData: `access: [96, "nope", 12, 32, 3, 128, 0, 0]`,
+			wantErr:  true,
+		},
+		{
+			name:     "legacy array with too many elements returns error",
+			yamlData: "access: [1, 2, 3, 4, 5, 6, 7, 8, 9]",
+			wantErr:  true,
+		},
+		{
 			name: "unmarshal map format with true values",
 			yamlData: `access:
   DownloadFile: true